package org.lionsoul.ip2region.ipv6;

import java.math.BigInteger;
import java.util.Arrays;

public class IpAddress {
    private byte[] m_ip = null;
    private boolean m_mapped = false;

    private IpAddress() {
    }

    public IpAddress(IpAddress ip) {
        m_ip = ip.m_ip;
        m_mapped = ip.m_mapped;
    }

    public IpAddress(String ip) {
        m_ip = textToNumericFormatV6(ip);
        if (m_ip == null) m_ip = textToNumericFormatV4(ip);
        if (m_ip == null)
            throw new IllegalArgumentException("非法IP地址");
    }

    public static IpAddress fromBytes(byte[] bytes) {
        if (bytes.length == INADDR4SZ) {
            IpAddress ip = new IpAddress();
            ip.m_ip = bytes;
            return ip;
        } else if (bytes.length == INADDR16SZ) {
            IpAddress ip = new IpAddress();
            ip.m_ip = bytes;
            ip.convertFromIPv4MappedAddress();
            return ip;
        } else {
            throw new IllegalArgumentException("非法IP地址");
        }
    }

    public static IpAddress fromBytesV4(byte[] b) {
        if (b.length == INADDR4SZ) {
            IpAddress ip = new IpAddress();
            ip.m_ip = b;
            return ip;
        } else {
            throw new IllegalArgumentException("非法IP地址");
        }
    }

    public static IpAddress fromBytesV6(byte[] b) {
        if (b.length == INADDR16SZ) {
            IpAddress ip = new IpAddress();
            ip.m_ip = b;
            return ip;
        } else if (b.length < INADDR16SZ) {
            IpAddress ip = new IpAddress();
            ip.m_ip = new byte[INADDR16SZ];
            System.arraycopy(b, 0, ip.m_ip, 0, b.length);
            ip.convertFromIPv4MappedAddress();
            return ip;
        } else {
            throw new IllegalArgumentException("非法IP地址");
        }
    }

    public static IpAddress fromBytesLE(byte[] b) {
        byte[] be = bswap(b);
        return fromBytes(be);
    }

    public static IpAddress fromBytesV4LE(byte[] b) {
        byte[] be = bswap(b);
        return fromBytesV4(be);
    }

    public static IpAddress fromBytesV6LE(byte[] b) {
        byte[] be = bswap(b);
        return fromBytesV6(be);
    }

    public byte[] getBytes() {
        return m_ip;
    }

    public byte[] getBytesLE() {
        return bswap(m_ip);
    }

    public BigInteger getBigInt() {
        byte[] bi = new byte[m_ip.length + 1];
        bi[0] = 0;
        System.arraycopy(m_ip, 0, bi, 1, m_ip.length);
        return new BigInteger(bi);
    }

    public boolean isValid() {
        return m_ip != null;
    }

    public boolean isIpv4() {
        return m_ip != null && m_ip.length == INADDR4SZ;
    }

    public boolean isIpv6() {
        return m_ip != null && m_ip.length == INADDR16SZ;
    }

    public boolean isSameFamily(IpAddress anIp) {
        if (m_ip == null || anIp == null) return false;
        if (this == anIp) return true;
        return m_ip.length == anIp.getBytes().length;
    }

    public boolean wasIPv4MappedAddress() {
        return m_mapped;
    }

    @Override
    public String toString() {
        if (m_ip == null)
            return "";
        else if (m_ip.length == INADDR4SZ)
            return numericToTextFormatV4(m_ip);
        else if (m_ip.length == INADDR16SZ)
            return numericToTextFormatV6(m_ip);
        else
            throw new RuntimeException("INTERNAL ERROR");
    }

    public boolean equals(IpAddress anIp) {
        if (m_ip == null || anIp == null) return false;
        if (this == anIp) return true;
        return Arrays.equals(m_ip, anIp.getBytes());
    }

    public int compareTo(IpAddress anIp) {
        int len = Math.min(m_ip.length, anIp.getBytes().length);
        for (int i = 0; i < len; i++) {
            int compare = compareUnsigned(m_ip[i], anIp.getBytes()[i]);
            if (compare == 0) {
                continue;
            }
            return compare;
        }
        return m_ip.length - anIp.getBytes().length;
    }

    private static int compareUnsigned(byte x, byte y) {
        return Byte.toUnsignedInt(x) - Byte.toUnsignedInt(y);
    }

    public static byte[] bswap(byte[] b) {
        byte[] rev = new byte[b.length];
        for (int i = 0, j = b.length - 1; j >= 0; i++, j--) {
            rev[j] = b[i];
        }
        return rev;
    }

    public void subOne() {
        BigInteger bi = getBigInt();
        bi = bi.subtract(BigInteger.ONE);
        byte[] b = bi.toByteArray();

        if (b.length >= m_ip.length) {
            System.arraycopy(b, 0, m_ip, 0, m_ip.length);
        } else {
            boolean minus = ((b[0] & 0x80) != 0);
            b[0] &= 0x7F;
            if (minus) {
                Arrays.fill(m_ip, (byte) 0xFF);
            } else {
                Arrays.fill(m_ip, (byte) 0);
            }
            System.arraycopy(b, 0, m_ip, m_ip.length - b.length, b.length);
        }
    }

    ////////////////////////////////////////////////////////////////////////////
    // sun.net.util.IPAddressUtil
    ////////////////////////////////////////////////////////////////////////////

    private static final int INADDR4SZ = 4;
    private static final int INADDR16SZ = 16;
    private static final int INT16SZ = 2;

    /*
     * Converts IPv4 address in its textual presentation form
     * into its numeric binary form.
     *
     * @param src a String representing an IPv4 address in standard format
     * @return a byte array representing the IPv4 numeric address
     */
    private static byte[] textToNumericFormatV4(String src) {
        byte[] res = new byte[INADDR4SZ];

        long tmpValue = 0;
        int currByte = 0;
        boolean newOctet = true;

        int len = src.length();
        if (len == 0 || len > 15) {
            return null;
        }
        /*
         * When only one part is given, the value is stored directly in
         * the network address without any byte rearrangement.
         *
         * When a two part address is supplied, the last part is
         * interpreted as a 24-bit quantity and placed in the right
         * most three bytes of the network address. This makes the
         * two part address format convenient for specifying Class A
         * network addresses as net.host.
         *
         * When a three part address is specified, the last part is
         * interpreted as a 16-bit quantity and placed in the right
         * most two bytes of the network address. This makes the
         * three part address format convenient for specifying
         * Class B net- work addresses as 128.net.host.
         *
         * When four parts are specified, each is interpreted as a
         * byte of data and assigned, from left to right, to the
         * four bytes of an IPv4 address.
         *
         * We determine and parse the leading parts, if any, as single
         * byte values in one pass directly into the resulting byte[],
         * then the remainder is treated as a 8-to-32-bit entity and
         * translated into the remaining bytes in the array.
         */
        for (int i = 0; i < len; i++) {
            char c = src.charAt(i);
            if (c == '.') {
                if (newOctet || tmpValue < 0 || tmpValue > 0xff || currByte == 3) {
                    return null;
                }
                res[currByte++] = (byte) (tmpValue & 0xff);
                tmpValue = 0;
                newOctet = true;
            } else {
                int digit = Character.digit(c, 10);
                if (digit < 0) {
                    return null;
                }
                tmpValue *= 10;
                tmpValue += digit;
                newOctet = false;
            }
        }
        if (newOctet || tmpValue < 0 || tmpValue >= (1L << ((4 - currByte) * 8))) {
            return null;
        }
        switch (currByte) {
            case 0:
                res[0] = (byte) ((tmpValue >> 24) & 0xff);
            case 1:
                res[1] = (byte) ((tmpValue >> 16) & 0xff);
            case 2:
                res[2] = (byte) ((tmpValue >> 8) & 0xff);
            case 3:
                res[3] = (byte) ((tmpValue >> 0) & 0xff);
        }
        return res;
    }

    /*
     * Convert IPv6 presentation level address to network order binary form.
     * credit:
     *  Converted from C code from Solaris 8 (inet_pton)
     *
     * Any component of the string following a per-cent % is ignored.
     *
     * @param src a String representing an IPv6 address in textual format
     * @return a byte array representing the IPv6 numeric address
     */
    private byte[] textToNumericFormatV6(String src) {
        // Shortest valid string is "::", hence at least 2 chars
        if (src.length() < 2) {
            return null;
        }

        int colonp;
        char ch;
        boolean saw_xdigit;
        int val;
        char[] srcb = src.toCharArray();
        byte[] dst = new byte[INADDR16SZ];

        int srcb_length = srcb.length;
        int pc = src.indexOf('%');
        if (pc == srcb_length - 1) {
            return null;
        }

        if (pc != -1) {
            srcb_length = pc;
        }

        colonp = -1;
        int i = 0, j = 0;
        /* Leading :: requires some special handling. */
        if (srcb[i] == ':')
            if (srcb[++i] != ':')
                return null;
        int curtok = i;
        saw_xdigit = false;
        val = 0;
        while (i < srcb_length) {
            ch = srcb[i++];
            int chval = Character.digit(ch, 16);
            if (chval != -1) {
                val <<= 4;
                val |= chval;
                if (val > 0xffff)
                    return null;
                saw_xdigit = true;
                continue;
            }
            if (ch == ':') {
                curtok = i;
                if (!saw_xdigit) {
                    if (colonp != -1)
                        return null;
                    colonp = j;
                    continue;
                } else if (i == srcb_length) {
                    return null;
                }
                if (j + INT16SZ > INADDR16SZ)
                    return null;
                dst[j++] = (byte) ((val >> 8) & 0xff);
                dst[j++] = (byte) (val & 0xff);
                saw_xdigit = false;
                val = 0;
                continue;
            }
            if (ch == '.' && ((j + INADDR4SZ) <= INADDR16SZ)) {
                String ia4 = src.substring(curtok, srcb_length);
                /* check this IPv4 address has 3 dots, ie. A.B.C.D */
                int dot_count = 0, index = 0;
                while ((index = ia4.indexOf('.', index)) != -1) {
                    dot_count++;
                    index++;
                }
                if (dot_count != 3) {
                    return null;
                }
                byte[] v4addr = textToNumericFormatV4(ia4);
                if (v4addr == null) {
                    return null;
                }
                for (int k = 0; k < INADDR4SZ; k++) {
                    dst[j++] = v4addr[k];
                }
                saw_xdigit = false;
                break;  /* '\0' was seen by inet_pton4(). */
            }
            return null;
        }
        if (saw_xdigit) {
            if (j + INT16SZ > INADDR16SZ)
                return null;
            dst[j++] = (byte) ((val >> 8) & 0xff);
            dst[j++] = (byte) (val & 0xff);
        }

        if (colonp != -1) {
            int n = j - colonp;

            if (j == INADDR16SZ)
                return null;
            for (i = 1; i <= n; i++) {
                dst[INADDR16SZ - i] = dst[colonp + n - i];
                dst[colonp + n - i] = 0;
            }
            j = INADDR16SZ;
        }
        if (j != INADDR16SZ)
            return null;
        m_ip = dst;
        convertFromIPv4MappedAddress();
        return m_ip;
    }

    ///**
    // * @param src a String representing an IPv4 address in textual format
    // * @return a boolean indicating whether src is an IPv4 literal address
    // */
    //private static boolean isIPv4LiteralAddress(String src) {
    //	return textToNumericFormatV4(src) != null;
    //}

    ///**
    // * @param src a String representing an IPv6 address in textual format
    // * @return a boolean indicating whether src is an IPv6 literal address
    // */
    //private boolean isIPv6LiteralAddress(String src) {
    //	return textToNumericFormatV6(src) != null;
    //}

    /*
     * Convert IPv4-Mapped address to IPv4 address. Both input and
     * returned value are in network order binary form.
     *
     * @param src a String representing an IPv4-Mapped address in textual format
     * @return a byte array representing the IPv4 numeric address
     */
    private void convertFromIPv4MappedAddress() {
        if (isIPv4MappedAddress(m_ip)) {
            m_mapped = true;
            byte[] newAddr = new byte[INADDR4SZ];
            System.arraycopy(m_ip, 12, newAddr, 0, INADDR4SZ);
            m_ip = newAddr;
        } else {
            m_mapped = false;
        }
    }

    /**
     * Utility routine to check if the InetAddress is an
     * IPv4 mapped IPv6 address.
     *
     * @return a <code>boolean</code> indicating if the InetAddress is
     * an IPv4 mapped IPv6 address; or false if address is IPv4 address.
     */
    private static boolean isIPv4MappedAddress(byte[] addr) {
        if (addr.length < INADDR16SZ) {
            return false;
        }
        if ((addr[0] == 0x00) && (addr[1] == 0x00) &&
                (addr[2] == 0x00) && (addr[3] == 0x00) &&
                (addr[4] == 0x00) && (addr[5] == 0x00) &&
                (addr[6] == 0x00) && (addr[7] == 0x00) &&
                (addr[8] == 0x00) && (addr[9] == 0x00) &&
                (addr[10] == (byte) 0xff) &&
                (addr[11] == (byte) 0xff)) {
            return true;
        }
        return false;
    }

    ////////////////////////////////////////////////////////////////////////////
    // java.net.Inet4Address
    ////////////////////////////////////////////////////////////////////////////

    /**
     * Converts IPv4 binary address into a string suitable for presentation.
     *
     * @param src a byte array representing an IPv4 numeric address
     * @return a String representing the IPv4 address in
     * textual representation format
     */
    private static String numericToTextFormatV4(byte[] src) {
        return (src[0] & 0xff) + "." + (src[1] & 0xff) + "." + (src[2] & 0xff) + "." + (src[3] & 0xff);
    }

    ////////////////////////////////////////////////////////////////////////////
    // java.net.Inet6Address
    ////////////////////////////////////////////////////////////////////////////

    /**
     * Convert IPv6 binary address into presentation (printable) format.
     *
     * @param src a byte array representing the IPv6 numeric address
     * @return a String representing an IPv6 address in
     * textual representation format
     */
    private static String numericToTextFormatV6(byte[] src) {
        StringBuilder sb = new StringBuilder(39);
        for (int i = 0; i < (INADDR16SZ / INT16SZ); i++) {
            sb.append(Integer.toHexString(((src[i << 1] << 8) & 0xff00) | (src[(i << 1) + 1] & 0xff)));
            if (i < (INADDR16SZ / INT16SZ) - 1) {
                sb.append(":");
            }
        }
        return sb.toString();
    }

}
